Functional role of DNRA and nitrite reduction in a pristine south Chilean <Emphasis Type="Italic">Nothofagus</Emphasis> forest |
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Authors: | T Rütting D Huygens C Müller O Van Cleemput R Godoy P Boeckx |
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Institution: | 1.Department of Plant Ecology,University of Giessen,Giessen,Germany;2.Department of Plant and Environmental Sciences,University of Gothenburg,Gothenburg,Sweden;3.Laboratory of Applied Physical Chemistry – ISOFYS, Faculty of Bioscience Engineering,Ghent University,Ghent,Belgium;4.Instituto de Ingeniería Agraria y Suelos,Universidad Austral de Chile,Valdivia,Chile;5.School of Biology and Environmental Science,UCD Dublin, Dublin 4,Ireland;6.Institute of Botany,Universidad Austral de Chile,Valdivia,Chile |
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Abstract: | Nitrite (NO2
−) is an intermediate in a variety of soil N cycling processes. However, NO2
− dynamics are often not included in studies that explore the N cycle in soil. Within the presented study, nitrite dynamics
were investigated in a Nothofagus betuloides forest on an Andisol in southern Chile. We carried out a 15N tracing study with six 15N labeling treatments, including combinations of NO3
−, NH4
+ and NO2
−. Gross N transformation rates were quantified with a 15N tracing model in combination with a Markov chain Monte Carlo optimization routine. Our results indicate the occurrence of
functional links between (1) NH4
+ oxidation, the main process for NO2
− production (nitritation), and NO2
− reduction, and (2) oxidation of soil organic N, the dominant NO3
− production process in this soil, and dissimilatory NO3
− reduction to NH4
+ (DNRA). The production of NH4
+ via DNRA was approximately ten times higher than direct mineralization from recalcitrant soil organic matter. Moreover, the
rate of DNRA was several magnitudes higher than the rate of other NO3
− reducing processes, indicating that DNRA is able to outcompete denitrification, which is most likely not an important process
in this ecosystem. These functional links are most likely adaptations of the microbial community to the prevailing pedo-climatic
conditions of this Nothofagus ecosystem. |
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Keywords: | Nothofagus betuloides 15N tracing model Nitrite (NO2 − ) N retention Dissimilatory nitrate reduction to ammonium (DNRA) Markov chain Monte Carlo sampling |
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